34 OPHTHALMOLOGY FOR VETERINARIANS 



muscles run horizontally and vertically and are in- 

 timately associated. 



The conjunctiva is the mucous membrane lining the 

 lids. It is strongly adherent to the tarsus. Superior 

 to the tarsus, it folds upon itself, forming a sort of culde- 

 sac, known as the fornix conjunctivae. This portion of 

 the conjunctiva contains numerous glands, resembling 

 the lacrimal gland in structure. The mucous glands 

 afford a secretion to lubricate the lids in the act of 

 winking and to moisten the cornea. 



The lids contain a portion of the lacrimal apparatus. 

 The outlet ducts from the lacrimal gland open at the 

 posterior portion of the superior and external part of the 

 upper lid. The drainage canals have their origin at 

 points known as the puncta lacrimalia. These are 

 situated near the inner angle of the Hds, nearly opposite 

 each other. Small canals run from these points, and 

 these unite at the lacrimal sac, internal to the inner 

 canthus. This sac leads into the nasal duct— a bony 

 canal— which terminates in the nasal cavity opposite 

 the middle turbinate. 



The anatomic arrangement of these structures is 

 somewhat different in quadrupeds and fowls. The 

 puncta, instead of pin-point openings near the border 

 of the lids, are large oval openings in the conjunctiva 

 of the Hds near the inner portion. The canals are also 

 much larger in proportion. 



The outer surface of the lids is subject to the same 



